25 Feb 2016

Patron Loses a Book The library patron reports to the librarian that she has lost a book. The lost a book. The librarian librarian prints out thelibrary record prints out the library record and asks patron to speak with the head librarian, who will arrange for the patron to pay a fee. The system will be updated to refl

ect lost book, and patron be updated to reflect lost book, and patron s' record is record is updated as well. The head librarian may authorize purchase of a replacement tape.

Formal Use Case

1

GOAL

Patron wishes to reserve a book using the online catalog

2

Primary Actor

Patron

3

Scope

Library system

4.

Level

User

5.

Pre Conditions

Patron is at the login screen

6.

Success end Conditions

Book is reserved

7.

Failure End Conditions

Book is not reserved

8.

Triggers

Patron logs into system

9.

Main Success Scenario

1. Patron enters account and password Scenario 2. System verifies and logs patron in System verifies and logs patron in 3. System presents catalog with search screen 4. Patron enters book title 5. System finds match and presents location choices to patron 6. Patron selects location and reserves book 7. System confirms reservation and re-presents catalog

10.

Extensions ( error scenarios)

2a. Password is incorrect (error scenarios) 2a.1 System returns patron to login screen 2a.2 Patron backs out or tries again

11.

Variations

Patron enters author or subject

Steps in creating a use case

1. Identify actors and their goals

What computers subsystems and people will drive our computers, subsystems and people will drive our system?

(actors)

2. What does each actor need our system to do ?

(goals )

3. Write the success scenario

– easiest to read and understand

– everything else is a complication on this

Capture each actor's intent and responsibility, from trigger to goal delivery

– say what information passes between them say what information passes between them

– number each line

4. List the failure extensions

5. List the variations

Use case description

1. How and when it begins and ends

2. The interactions between the use case and its actors, including including when the interaction interaction occurs and what is exchanged .

3. How and when the use case will need data from or store data to the system .